Chapter 10.SE, Problem 43AP

Interpretation Introduction

Interpretation:

Given that addition of HBr to a double bond with an ether substituent occurs regiospecifically to give a product in which the –Br and –OR are bonded to the same carbon. Two carbocation intermediates possible in this electrophilic addition reaction are to be drawn. The formation of the product is to be explained using the concept of resonance.

Concept introduction:

In electrophilic addition reactions the first step involves the abstraction of the positively polarized hydrogen of H-Br by the π electrons of the double bond to yield a more stable carbonium ion eliminating the bromine as bromide ion. In the second step the bromide ion attacks the carbocation to yield the product.

To draw:

The structures of the two carbocation intermediates possible in the electrophilic addition of HBr into methoxy cyclohexene.

To explain:

The formation of the regiospecific product using the concept of resonance.